Many catalysts have been proposed as catalysts for use in the oxidation reactions, ammoxidation reactions and oxidative dehydrogenation reactions of organic compounds. For example, catalysts containing molybdenum and bismuth are disclosed in JP-B-36-3563 (the term "JP-B" as used herein refers to an "examined Japanese patent publication") (corresponding to U.S. Pat. No. 2,941,007), JP-B-36-5870 (U.S. Pat. No. 2,904,580), JP-B-38-17967 (U.S. Pat. No. 3,226,422), JP-B-47-27490 (U.S. Pat. No. 3,959,384), JP-B-48-43096 (U.S. Pat. No. 3,766,092), JP-B-51-33888 (U.S. Pat. No. 4,503,001), JP-B-53-23813 (U.S. Pat. No. 3,894,091), JP-A-55-13187 (the term "JP-A" as used herein refers to a "published unexamined Japanese patent application") (corresponding to U.S. Pat. No. 4,212,760) and JP-B-60-36812 (U.S. Pat. Nos. 4,377,534 and 4,600,541). Catalysts containing molybdenum and tellurium are disclosed in JP-B-37-11008 (U.S. Pat. No. 3,164,626) and JP-B-39-8214 (British Patent 1,016,031). Catalysts containing antimony and tin are disclosed in JP-B-37-14075 (U.S. Pat. No. 3,269,957) and JP-B-47-40958. Catalysts containing antimony and uranium are disclosed in JP-B-40-24367 (U.S. Pat. No. 3,308,151) and JP-B-47-19764. JP-A-56-97550 (corresponding to European Patent 32,618B) proposes catalysts containing a metal antimonate component and a bismuth molybdate component.
Further, catalysts containing antimony and iron as essential elements are disclosed in JP-B-38-19111. Many improvements on these catalysts have been made. For example, JP-B-45-32685 (U.S. Pat. No. 3,542,843), JP-B-46-2804 (U.S. Pat. No. 3,668,147), JP-B-46-2805 (U.S. Pat. No. 3,591,620), JP-B-46-2806, JP-B-46-2807, JP-B-46-3564, JP-B-47-19765 (U.S. Pat. No. 3,716,496), JP-B-47-19766, JP-B-47-19767, JP-B-53-18014 (U.S. Pat. Nos. 3,988,359 and 4,083,804) and JP-B-57-26592 (U.S. Pat. No. 4,370,279) propose catalysts to improve prior arts.
In addition, JP-A-57-114560, JP-A-60-90044, JP-B-62-46538 (U.S. Pat. No. 4,309,361) and JP-A-3-26342 (U.S. patent application Ser. No. 07/540,729, filed on Jun. 20, 1990, now U.S. Pat. No. 5,094,990, and European Patent Publication 404,529A1) propose catalysts containing antimony and iron.
On the other hand, processes for preparing these catalysts are disclosed in, for example, JP-B-42-22476 (U.S. Pat. No. 3,341,971), JP-B-47-18722 (U.S. Pat. No. 3,657,155), JP-B-47-18723 (U.S. Pat. No. 3,686,138) and JP-B-52-42552 (U.S. Pat. No. 4,049,575).
Since the industrial output of products is high in the field of the production of particularly acrylonitrile, acrolein and methacrylonitrile to which the present invention belongs, a slight increase by 1% in the yields of the desired products or a slight improvement in the physical properties of the catalyst such as catalyst strength gives remarkable commercial and economic effects. Accordingly, it is an important matter that an improvement in the performance of the catalysts to be used for the above described reactions is made.
Conventional catalysts have many disadvantages in that the yields of the desired products are insufficient, a change with time is great, reproducibility is poor, and the catalysts do not always satisfy both activity and physical properties. Among the above described conventional catalysts, catalysts containing iron and antimony described in JP-B-53-18014 (U.S. Pat. Nos. 3,988,359 and 4,083,804) and JP-A-3-26342 (U.S. patent application Ser. No. 07/540,729 and European Patent Publication 404,529A1) are excellent ones and have many advantages. However, when these catalysts contain a relatively large amount of a molybdenum component as in the former, there is a problem that the yield of the desired product acrylonitrile is lowered as described, for example, in the experimental examples (catalysts 17 and 18 and catalyst 22) of the former reference. Further, when these catalysts contain a relatively large amount of a phosphorus component as in the latter, there is a problem that the yield of the product obtained by the ammoxidation of olefinic hydrocarbons is lowered as described, for example, in the experimental examples (Examples 7 and 8) of the latter reference.
The present invention has been performed to improve the activity and physical properties of an iron-antimony-containing catalyst having a relatively high molybdenum content.